Iron, Total
Iron, Total
IronTot_PP_Other_FMO_Eng_Ody.fm Page 3 of 4
Sample Collection, Storage and Preservation
Collect samples in acid-washed glass or plastic bottles. To preserve samples,
adjust the sample pH to 2 or less with hydrochloric acid (about 2 mL per liter)
(Cat. No. 134-49). Samples preserved in this manner can be stored up to six
months at room temperature. If only dissolved iron is to be reported, filter
sample immediately after collection through a 0.45-micron filter or equivalent
medium before adding hydrochloric acid.
Before testing, adjust the sample pH to 3–5 with 5.0 N Sodium Hydroxide
Standard Solution (Cat. No. 2450-32). Do not exceed pH 5 as iron may
precipitate. Correct test results for volume additions; see Section 3.1.3 Correcting
for Volume Additions on page 29.
Accuracy Check
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch
Options. Touch Standard Additions. A summary of the standard
additions procedure will appear.
3. Touch
OK to accept the default values for standard concentration, sample
volume, and spike volumes. Touch
Edit to change these values. After values
are accepted, the unspiked sample reading will appear in the top row. See
Standard Additions in the instrument manual for more information.
4. Open an Iron Voluette
®
Ampule Standard, 50-mg/L Fe.
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-41)
with 50 mL of sample. Use the TenSette
®
Pipet to add 0.1 mL, 0.2 mL, and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. Analyze each sample spike as described in the procedure above, starting with
the 0.1 mL sample spike. The iron concentration should increase by
0.10 mg/L. Accept each standard additions reading by touching
Read. Each
addition should reflect approximately 100% recovery.
7. After completing the sequence, touch
Graph to view the best-fit line through
the standard additions data points, accounting for matrix interferences. Touch
View: Fit, then select Ideal Line and touch OK to view the relationship between
the sample spikes and the “Ideal Line” of 100% recovery.
See Section 3.2.2 Standard Additions on page 32 for more information.
Standard Solution Method
1. Using Class A glassware, prepare a 0.40-mg/L iron standard solution by
pipetting 4.00 mL of Iron Standard Solution, 100-mg/L, into a 1-liter
volumetric flask. Dilute to the mark with deionized water. Prepare this
solution daily. Perform the iron procedure as described above.
2. To adjust the calibration curve using the reading obtained with the
0.40-mg/L Fe Standard Solution, touch
Options on the current program
menu. Touch
Standard Adjust: Off.
3. Touch
On. Touch Adjust to accept the displayed concentration. If an alternate
concentration is used, touch the number in the box to enter the actual
concentration, then touch
OK. Touch Adjust.
See Section 3.2.4 Adjusting the Standard Curve on page 40 for more information.
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